Quote:
Originally Posted by someone123
One model is:
Congestion = Population / (Roads + Transit)
You can critique this model but I bet it's more informative than the implicit model people have when they talk about induced demand and other likely second-order effects. I think the fact we've lost sight of the basics so much says something about our culture and the sort of typically not very technically minded people who get bandwidth in the public debate.
In Toronto, roads have been almost unchanged, transit has maybe moderately improved, and population has grown significantly. You can argue about which factor is to blame but it's really 3 factors in combination, and the easiest to adjust was probably the population factor since that's been determined directly by a federal policy. I would argue that since the situation is so bad, it's good to try to improve all of these factors. I'm pro transit but I'm skeptical that we can have sustainable highly functional cities growing at 3% with basically 2000's or older road networks. It's also worth pointing out that we're mass importing workers for Tim Hortons while we can't seem to build infrastructure which can actually be a good use of TFWs.
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While there's definitely some truth to that, it's also often misleading. The main thing people miss is that roads and transit are often the same thing because the majority of transit usage in most places happens on the road rather than in other places like subways. So the same road network can be made to handle fewer or greater numbers of people based on the percentage of density of people using the roads. And the biggest thing that determined density is the number of people per vehicle with transit vehicles being the champions in that regard. If you go from having one out of 100 vehicles being a transit vehicle like a bus or streetcar to one in 50, then you're ability to transport people increases drastically without adding any new road lanes at all. Same thing if you go from one in 50 road vehicles being transit to one in 25 since every bus that's added is the equivalent of say 40 or 50 cars.
In a place that has narrow roads there's obviously going to be a lower maximum capacity then a place with wider roads, but in North America we tend to have wider roads (and stroads) than in many other regions. So we're capable of carrying significantly more people with our existing road network and without adding other transit modes even if those other modes are desirable to have. So it's a political decision to use road space less efficiently and require additional capacity to be built pre-maturely in the form of more/wider roads or transit ROWs like subways. The problem of course is that from a political standpoint many people falsely believe that if you take away a lane of road space from general traffic and dedicate it to transit (or impose other restrictions on general traffic) that it will reduce the overall capacity of the road and increase congestion when in reality it actually increases road capacity by changing the vehicle fleet balance to one that's more efficient (buses and street cars versus private automobiles allowing higher capacity vehicles to move more quickly).
It's basically the same as with land use and density. Just like a piece of land can hold significantly more people if developed using denser building stock like apartment buildings or townhouses, a road can carry significantly more people by having using multi-passenger vehicles. And the same way you can boost residential density by adding a few apartment building into the mix, you can boost road density by adding more buses into the mix. So you can look at a congested road and tell how close it is to its maximum passenger carrying capacity by seeing the proportion of vehicles with few or one passenger compared to mutli-passenger vehicles. Just like you can look at a piece of land and tell how close it is to its maximum density by seeing the ratio of fully detached houses compared to multi-unit. So just like a place can't claim it's out of land and can't handle more people when it's mostly low-density detached houses, we also can't claim that we're out of road space and can't transport more people when the majority of vehicles are private automobiles. So while more transit infrastructure is great and I want it, it isn't true that more infrastructure is "necessary" in order to transport more people. It's just politically necessary rather than functionally necessary.
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